/* Copyright (c) 2009 Matthias Kaeppler
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package oauth.signpost.signature;

import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;
import java.util.Map;

import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import oauth.signpost.OAuth;
import oauth.signpost.exception.OAuthMessageSignerException;
import oauth.signpost.http.HttpRequest;

@SuppressWarnings("serial")
public class HmacSha1MessageSigner extends OAuthMessageSigner {

	private static final String MAC_NAME = "HmacSHA1";

	@Override
	public String sign(HttpRequest request, Map<String, String> oauthParameters)
			throws OAuthMessageSignerException {
		try {
			String keyString = OAuth.percentEncode(getConsumerSecret()) + '&'
					+ OAuth.percentEncode(getTokenSecret());
			byte[] keyBytes = keyString.getBytes(OAuth.ENCODING);

			SecretKey key = new SecretKeySpec(keyBytes, MAC_NAME);
			Mac mac = Mac.getInstance(MAC_NAME);
			mac.init(key);

			String sbs = computeSignatureBaseString(request, oauthParameters);
			byte[] text = sbs.getBytes(OAuth.ENCODING);

			return base64Encode(mac.doFinal(text)).trim();
		} catch (GeneralSecurityException e) {
			throw new OAuthMessageSignerException(e);
		} catch (UnsupportedEncodingException e) {
			throw new OAuthMessageSignerException(e);
		}
	}
}
